In the past few weeks, scientific sleuths in Portland helped solve a mysterious outbreak of E. coli in a multi-state investigation that involved a wedding in Washington state, dumpster diving in Yamhill County and cheese samples at a gourmet store in Seattle.

The investigation was sparked by two unrelated cases in Roseburg and ended in an outbreak that sickened eight people in four states and the recall of all of cheese made by a highly respected raw milk cheesemaker in north-central Washington.

Getting to that recall -- of Sally Jackson cheese -- took a lot of footwork, phonework and guesswork on the part of Oregon Public Health and other state and federal agencies.

To this day, no one sickened remembers consuming Sally Jackson cheese. But epidemiologists managed to pinpoint it anyway.

"I can't recall another outbreak with so many cases and a multi-state outbreak with none of the cases remembering eating the food," said William Keene, senior epidemiologist with Oregon Public Health.

About two weeks ago, Keene found out about two cases of E. coli O157 in Roseburg. Both were women in their early 60s. They didn't know each other but their demographic similarity sent up red flags, indicating a possible wider outbreak.

Keene asked a French physician, Dr. Mathieu Tourdjman, who's currently working at Oregon Public Health in Portland, to investigate.

Tourdjman, who arrived in the United States in August, asked the women what they had eaten based on a nine-page questionnaire developed by Keene. It included foods Tourdjman had never heard of -- such as chicken fingers and canned cheese.

"Cheez Whiz was one of foods that he got stuck on," Keene said. "He was unfamiliar not only with the product but also with the concept."

Tourdjman quickly caught on. Under Keene's guidance, he discovered another E. coli case in Vancouver. Turns out that that woman and one of the women in Roseburg had dined one day apart at Clarklewis Restaurant in Southeast Portland.

Not only that, they had both ordered the artisan cheese plate as a starter.

Clarklewis officials could not identify the cheese they ate. But the restaurant's invoices provided a list of suspects. They included Sally Jackson cheese.

"That was the start, and it turned out to be critical," Keene said. "We assumed that whatever was causing the outbreak was at the restaurant."

Then another Washington connection popped up with a woman who had shopped at Calf & Kid, an artisan cheese store in Seattle.

With Sally Jackson on their radar, the Oregon epidemiologists discovered more cases, including a man in Vermont and one in Seattle.

The Vermont man had visited his uncle in Seattle and eaten at Palace Kitchen, a high-end restaurant that serves Sally Jackson cheese. And the man in Seattle had attended a wedding in Tonasket, Wash., just south of Oroville. The wedding featured local cheese -- probably from Sally Jackson.

The scientists had circumstantial evidence. Now, they needed proof. Keene sought Sally Jackson cheese from Oregon restaurants to test for E. coli. Very few had any. Tina's Restaurant in Dundee had thrown some away. The owner retrieved it by diving into her Dumpster.

In the end, at least two samples of Sally Jackson's cheese tested positive for E. coli O157:H7, confirming it was the source of the outbreak that sickened eight and involved investigators from four states and the Food and Drug Administration.

Last Friday, less than two weeks after Tourdjman started the investigation, Jackson pulled all her cheese off the market.

"I voluntarily recalled my cheese to keep other people from getting sick," she told The Oregonian.

The recall was followed by an FDA inspection report that cited Jackson for unsanitary practices, such as inadequate hand-washing facilities and manure on floors.

Jackson, who turns 65 in a few weeks, is closing down.

"I would have preferred to have (retired) on my own terms but it's not to be," she said.

For Tourdjman, who comes from a country famous for its food, the investigation was an eye-opener.

Food is recalled in France but that country does not have a wealth of epidemiologists to investigate outbreaks.

"We don't have such a developed public health system," he said, "and all those epidemiologists know each other and are perfectly happy to cooperate."